"Remember, if there's any danger, you must stop immediately. Do you understand?" Itachi’s face remained clouded with concern.

"Let's begin. I’ll try compressing my chakra one more time on my own. If it doesn’t work, you can assist me by transferring your chakra."

Sasuke, unwilling to give up, decided to make another attempt. He sat cross-legged on the grass, preparing to start.

"Shadow Clone Technique!" Itachi swiftly formed a series of hand seals, creating four shadow clones that positioned themselves at the corners of the training ground. It was clear that Itachi was taking precautions to ensure absolute silence—any disruption could spell failure. He scanned the surroundings, finding nothing amiss, and then took his place behind Sasuke, watching intently as Sasuke began to compress his chakra.

"It’s still not working!" An hour later, Sasuke realized that success was beyond his reach alone. He opened his eyes, resigned to asking for help.

"Itachi, I need your assistance," Sasuke said, his voice laced with frustration.

"Understood." Itachi placed his hands on Sasuke's back, ready to transmit his chakra when a sudden thought crossed his mind.

"Wait a moment," Itachi said urgently just as Sasuke was about to close his eyes and try again.

"What’s wrong?" Sasuke’s face was full of confusion, his heart sinking at the possibility that Itachi might stop him out of safety concerns.

"Just to be safe, hold a soldier pill in your mouth." Itachi pulled a small, black pill from his pouch and handed it to Sasuke.

Taking the pill, Sasuke listened as Itachi continued, "Soldier pills allow a shinobi to fight for three days and nights without rest, keeping them alert, but they take a severe toll on both body and mind. I wouldn’t let you take this if it weren’t necessary."

After explaining the effects of the pill, Sasuke placed it in his mouth, and Itachi once again placed his hands on Sasuke’s back, slowly channeling his chakra into him.

"Let’s begin," Sasuke whispered.

He first gathered all of his chakra into his lower abdomen, then slowly guided Itachi’s chakra to envelop his own, beginning the process of compression.

Ten minutes later, Sasuke had compressed his chakra into a sphere the size of a fist. After an hour, the sphere had shrunk to the size of a thumb. The density was so immense that the deep blue chakra had turned black. Two hours later, though it appeared unchanged, a closer look revealed it was still shrinking. Three hours passed, and there was no significant change.

"Damn it, am I still not there? I’m almost at my limit," Sasuke thought, sweat pouring down his face, veins bulging on his forehead, giving him a terrifying appearance. Gritting his teeth, he swallowed the soldier pill.

Four hours later, still no progress.

"Am I at my limit again?" Sasuke’s body trembled uncontrollably. After four hours of intense focus, his mental and physical energy were nearly depleted. During this time, unable to use his own chakra, he had relied entirely on Itachi’s, which, being foreign, had drained his mental strength even more. To endure for four hours was already an extraordinary feat, but continuing was impossible. If Sasuke lost control of the chakra, the compressed sphere could explode, causing him great harm.

"Am I really going to give up? If I do, Itachi will never let me attempt this again after witnessing the danger. And I can’t succeed on my own. No, I’ve worked too hard for this. After a month of effort, if I give up now, I may never have another chance." Sasuke clenched his teeth, opening his eyes with renewed determination.

"If I don’t want to give up, then I have to give it my all."

A look of resolve flashed across Sasuke’s face, one that brooked no failure, only success. He closed his eyes and refocused on his chakra.

"Sasuke, stop! Any further and it will be too dangerous," Itachi warned, sensing the growing peril, his face etched with anxiety.

"Itachi, lend me your strength," Sasuke replied with unwavering resolve, ignoring Itachi’s warning.

"No!" Sweat streamed down Itachi’s face, whether from fear for Sasuke or from the exertion of sustaining his chakra, it was unclear.

Itachi wanted to refuse, but Sasuke had already turned his full attention to his chakra, ignoring any protest. Since Sasuke was in control of the chakra, Itachi couldn’t intervene. He could only watch as Sasuke attempted another compression.

Itachi could withdraw his hands, stop the chakra transfer. But without his chakra, Sasuke’s would immediately spiral out of control. Itachi knew this, and so he dared not make a move, his eyes fixed on Sasuke.

"Has it been ten minutes? Have I completely exhausted my mental energy? Then let’s do this—success or failure, it all comes down to this." Sasuke didn’t rush to compress the chakra. Instead, he slowly drew more from Itachi, gathering it just outside his lower abdomen, preparing for the final push.

Ten minutes later, he had amassed a chakra volume equivalent to that of a mid-level ninja. Sasuke wanted to gather more, but his mental energy was at its limit. "Boom..." His abdomen began to quake violently, blood trickling from the corner of his mouth, a stark contrast that was strangely beautiful.

"Sasuke, you must not fail," Itachi whispered, feeling the tremors in Sasuke’s body, his own heart quaking with fear. His face was a mix of guilt and deep worry.

"Damn it, it’s still not working? Then this is it, the final strike!" Sasuke funneled every last ounce of chakra into his lower abdomen.

"I must succeed!" Both Sasuke and Itachi thought in unison. The chakra sphere within Sasuke’s abdomen finally reacted, slowly shrinking... "Ah!" Sasuke’s body began to bleed from every pore. His mental and physical strength had reached their absolute limits, and now even his body was giving out.

"Boom..." Sasuke slowly collapsed forward.

"At last, I’ve succeeded. Then it was all worth it." Sasuke smiled just before he lost consciousness.